Dry amorphous silica product with inert carrier

ABSTRACT

A dry product that permanently removes oil and oil stains from liquid or dry surfaces and is environmentally safe. The dry product is formed by mixing efficacious proportions of untreated amorphous silica with a dry, inert organic, inorganic or synthetic carrier, or combinations of said carriers. Suitable inert carriers include, but are not limited to, (a) inert inorganic carriers including, but not limited to, clays, perlite, vermiculite, crushed glass, volcanic ash and sand; (b) inert organic carriers, including, but not limited to, peat moss, straw, hay, sawdust, ground corncobs, flours, and coconut coir, and (c) inert synthetic carriers, including, but not limited to, polyurethane, polyethylene and polypropylene. The dry product can be applied directly to oil stains either on a hard surface, such as concrete or asphalt, or to oil spills on water.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. application Ser.No. 12/035,362, entitled “Dry Amorphous Silica Product With InertCarrier To Remove Oil From Surfaces” filed Feb. 21, 2008 and now issuedas U.S. Pat. No. 7,922,913, the disclosures of which are herebyexpressly incorporated by reference for all purposes in its entirety.

FIELD OF THE INVENTION

The present invention relates to environmentally protective, self-actingoil absorbent products which can be applied to hard surfaces, such asconcrete, asphalt, pavers, countertops and wood, as well as oil spillsfrom water surfaces. The products have, as components, dry, syntheticamorphous silica combined with a dry, inert carrier. The inert carriermay be synthetic, organic, or inorganic or a combination of thesecarriers.

BACKGROUND OF THE INVENTION

Dry, granular adsorbent materials are used for a variety of industrialand household purposes, including oil absorption. Nonetheless, theabsorption and removal of oil often creates environmental issues. Infact, many authorities have banned the flushing of environmentallyhazardous oil residues into storm drain systems which flow into ournatural ecosystems. Even when contaminated residues collected from andcombined with cleaning materials are discarded into solid waste dumpsites, they represent eco-hazards by having their soluble, ionizingcontaminants as well as non-soluble, unbound oil and chemicalcontaminates bleed and leach into the soil and groundwater.

U.S. Published Patent Application No. US2006/0276361A1 refers to surfacecleaning and contaminant absorption compositions. While these complexcompositions appear friendlier to the environment than othercompositions in the art, they contain Zeolite® (chemically known aspotassium-calcium-sodium aluminosilicate), fly ash, carbonates,charcoal, and/or surfactants. The surfactants are described as an activeagent to aid absorption, i.e., by increasing the wetting and emulsifyingcapacity of the compositions. The negative aspect of these surfactantsis that they aid the contaminant to leach out when disposed of and thusis not eco-compatible. The concrete asphalt cleaning art described inthis application also mentions a solvent, preferably diproplylene glycolmonomethyl, to dissolve surface contaminants. These solvents also aidthe bleeding/leaching of contaminants into the soils of the solid wastesite and become contaminants themselves.

Other prior art cites various adsorbents, absorbents and cleaningmaterials. The disadvantage of these compositions is that they producecomplex contaminated residues unsuitable for disposal in sanitary/stormdrains.

For example, Cervero's U.S. Pat. No. 6,827,792 B2 discloses the creationof admixtures of inorganic salts with silica gel (amorphous silica) toabsorb liquid wastes, oils and hydrocarbons. Similarly, WO/2007/104955describes carpet cleaning compositions that contain at least 30% ofprecipitated or fumed silica component (also amorphous silica), withpreferential amounts greater than 50% by weight, to which is addedalkali metal salts and an active detergent. Dozens of types ofdetergents are listed including eco-harmful phosphates which arediscouraged or banned in most states. The use of ionizing salts in theseformulations causes high solubility and thereby detracts from theability of the amorphous silica to absorb liquid wastes, oils andhydrocarbons. Moreover, the ionizing salts can cause any liquid wastes,oils and hydrocarbons absorbed by the amorphous silica to bleed andleach away when placed in waste dumps.

U.S. Pat. No. 5,951,784 teaches scrubbing with detergent, phosphates andother surfactants to clean oil off concrete followed by rinsing withwater and subsequently, in a second application, introduction of a fineclay absorbent to remove the stain. This is onerous and results inunacceptable contaminated waste, unfit for disposal.

U.S. Pat. No. 5,723,424 pertains to a concrete cleaning mixturedescribed as two components. The first component consists of a granularOil-Dri® type absorbent attapulgite clay material combined with granularcat litter/attapulgite-type clay. This is rubbed onto the oilcontamination and then removed. The second component consists ofkaolin-type clay and finely ground clay dust that absorbs the oil frompores and crevices. Use of this product is laborious and producesunbound contaminated waste that easily allows oil to bleed/leach whendisposed of in landfill.

U.S. Pat. No. 7,041,221 B2 uses crushed glass as an absorber of oil fromsurface water whereby the crushed glass sinks when it is coated with oiland is subsequently recovered, then recycled into roof shingles orasphalt. The disclosed recycling acknowledges the eco-threat of thecontaminated absorbate, which cannot be discarded into solid waste dumpsites because the oil will bleed into the soil since the oil is notpermanently bound to the crushed glass. The same is true if this methodhad been used to remove oil from a solid surface.

U.S. Published Patent Application No. US2005/0028839 A1 teaches a methodfor treating spills on roadways by using biodegradable absorbentmaterial consisting of peat moss and coconut coir to absorb and removespills. U.S. Pat. No. 6,391,120 B1 describes use of coconut coir pith assorbent. U.S. Pat. No. 4,670,156 discloses use of hydrophobic sorbent,particularly expanded reject fibers that absorb even heavy oils. U.S.Pat. No. 5,244,503 uses polyvinyl acetal to bind to absorbate andconfirms “the adsorbent laden with absorbate should here arise in themost particulate or compacted form possible without adhering liquid oilresidues, so that it can be collected mechanically and passed todisposal.” All sorts of synthetics and other diverse oil sorbents suchas polypropylene plastic foams, matting, and mixtures of fibers canabsorb oil from water surfaces. They unfortunately all have thedisadvantage of leaching liquid oil residues.

Numerous methods for removal of oil spills are well known andestablished in the art. The U.S. Environmental Protection Agency (EPA),for example, outlines response techniques at their websitewww.epa.gov/oilspill/oiltech.htm Use of natural and synthetic sorbentmaterials are described including advantages and disadvantages.

There is a great need for oil and oil stain removal that is done withmaterials that are totally compatible with the environment, easy toproduce, easy to remove and, when discarded, does not bleed or leachback into the environment.

BRIEF SUMMARY OF THE INVENTION

The present invention provides for dry products that permanently removeoil, oil stains and/or hydrocarbons from liquid or dry surfaces and areenvironmentally safe. In the preferred embodiment, the dry products ofthe present invention are formed by mixing efficacious proportions ofuntreated amorphous silica with a dry, inert organic, inorganic orsynthetic carrier, or combinations of said carriers. Suitable inertcarriers include, but are not limited to, (a) inert natural, inorganiccarriers including, but not limited to, clays (e.g., Kaolin type clayand Fuller's clay—Attasorb 30/60 RVM attapulgite, BASF Corp., Quincy,Fla.), perlite, vermiculite, crushed glass, volcanic ash and sand (RMCPacific Materials, Pleasanton, Calif. kiln dried Monterey sand, 30 mesh“Lapis Lustre”); (b) inert organic carriers including, but not limitedto, peat moss, straw, hay, sawdust, ground corncobs, flours, and coconutcoir, and (c) inert synthetic carriers, including, but not limited to,polyurethane, polyethylene and polypropylene.

The dry products of the present invention can be applied directly to oilstains either on a hard surface, such as concrete or asphalt, or to oilspills on water. Use of an inert carrier with the amorphous silica makesthe dry product of the present invention both oleophilic andhydrophilic. This allows the dry product of the present invention to beuniquely (a) self-acting, (b) highly efficient and (c) totally containthe bound absorbates (e.g., oil). While some inert carriers used in dryproduct embodiments of the present invention may absorb some oil, theamorphous silica combines with that oil in a matrix to prevent leachinguntil the oil is eventually bio-remediated in a natural way (e.g., atthe disposal site).

These and other novel advantages and features of the present inventionwill be appreciated and understood from consideration of the followingdetailed description of preferred and varied forms of the concept.

DETAILED DESCRIPTION OF THE INVENTION

The oil and oil stain removal products of the present embodimentsconsist of optimal proportions by weight of untreated amorphous silica,which is the self-acting absorber/binder, combined with a suitable inertcarrier.

Amorphous silica is also known as fumed silica, fumed silicon dioxide,colloidal silica, synthetic silica, colloidal silicon dioxide andpyrogenic amorphous silica. In powder form, this type of silica is fine,white, extremely fluffy and dusty, making it very difficult to apply anduse as a powder by itself, especially in open air applications. In mostcommercial use, amorphous silica is incorporated into liquid productsfor rheology control, texture or to reinforce polymers and elastomers.Since amorphous silica can be used as an FDA approved additive inpowdered food products, it is not toxic.

Untreated synthetic amorphous silica can be produced by the vapor phasehydrolysis of silicon tetrachloride in a hydrogen-oxygen flame. Thecombustion process creates silicon dioxide molecules, which condense toform particles. The particles collide, attach and sinter together. Theresult of these processes is a three dimensional, branched chainaggregate with a length of approx. 0.2-0.3 microns. As these cool,further collisions result in mechanical entanglement of the chains,termed agglomeration. The ultimate agglomerate size is less than 325 U Smesh (44 microns). This silica is amorphous in structure as opposed tocrystalline. Therefore, it does not have the serious health problemsassociated with crystalline silica dust.

Another form of amorphous silica is precipitated silica. Precipitatedsilicas are synthesized by acidifying sodium silicate. The precipitatedsilicas distinguish themselves from silica gels on the basis of porestructure. Precipitates typically have a broad meso/macro porestructure, whereas gels have a more narrow microporous or mesoporousstructure. While all untreated amorphous silicas comprise preferredembodiments, fumed silica is especially preferred. Among other worldwidesuppliers of amorphous silica are Cabot Corp., Tuscola, Ill. (under thetradenames CAB-O-SIL® and EH-5) and W. R. Grace, Conn.

The amorphous silica component of the present invention is impracticalto apply to oil spills and stains as a stand alone composition. Its lowdensity, dusty fluffiness makes powdered amorphous silica very difficultto control. Moreover, the dust can irritate the respiratory tract, eyesand can cause dry, cracked skin.

In the present invention, one or more inert carriers are combined withthe amorphous silica to provide specific area application control,eliminate dusting and un-agglomerating powder fluff balls. Surprisingly,the use of inert carriers greatly enhances absorption results, probablyby the carrier spacing individual silica particles. The inventor hasfound acceptable results where amorphous silica comprises between 0.2%to 35% of the dry product weight. Through routine experimentation, thoseof skill in the art can obtain successful results with other proportionsof amorphous silica to inert carrier, depending upon the inert carrierselected. Ideally, in forming the dry product mixture, one of skill inthe art wants to optimize through routine experimentation three factors:(1) absorption, (2) binding, and (3) acceptable non-dusting.

A number of different inert carriers can be combined with amorphoussilica to form the dry, oil absorbing product of the present invention.All of the suitable carriers of the present invention are “inert” in thesense that they are passive and chemically non-reactive (i.e., notreadily reactive with other elements or compounds). Suitable inertcarriers for the present invention include, but are not limited to, (a)inert, natural, inorganic carriers including, but not limited to, clays(e.g., kaolin type clay and Fuller's clay—Attasorb 30/60 RVMattapulgite, BASF Corp., Quincy, Fla.), perlite, vermiculite, crushedglass, volcanic ash and sand (RMC Pacific Materials, Pleasanton, Calif.kiln dried Monterey sand, 30 mesh “Lapis Lustre”); (b) inert organiccarriers, including, but not limited to, peat moss, straw, hay, sawdust,ground corncobs, flours, and coconut coir; (c) inert synthetic carriers,including, but not limited to, polyurethane, polyethylene andpolypropylene. These carriers may be combined with the amorphous silicaindividually or in various combinations. Moreover, these carriers may ormay not act as granular sorbents since their main function is as carrierfor the silica.

For oil stain removal from surfaces, the selection of carrier can bechosen with regard to protecting the surface from damage. For hardsurfaces like concrete, concrete pavers and asphalt (roads), sand is agood choice for an inert carrier. Application can be by shaker containeror broom spread. Sweeping up residue from this type of dry product willnot harm the surface. For fine stone flooring, counter tops, furniture,trivets and the like, a soft, non-abrasive clay carrier is moreappropriate.

The embodiments of the present invention include, but are not limitedto, all those materials mentioned as inert carriers. A person skilled inthe art can select combinations that fit oil stain and spill remediationaccording to needs.

A first application of the dry product of the present invention is for ahard surface. In this application, dry, granular product of the presentinvention is sprinkled onto or spread onto the oil contaminated hardsurface, such as concrete pad, pavers, roads and asphalt surfaces. Theactive ingredient, synthetic amorphous silica, in a most startling,self-acting, vigorous manner absorbs the oil contaminant like (in ananalogy) iron filings are drawn to a magnet. The self-acting absorptionbegins within seconds upon a liquid spill and may take minutes orseveral hours to complete depending on the severity of a stain. Inaddition to road surfaces, such as concrete or asphalt, the dry productsof the present invention can also be applied to household surfaces, suchas wood floors, wood furniture, plastic furniture, carpeting, cuttingboards and granite countertops.

The term oil refers to the group comprising crude oil, tar oil, bunkeroil, lubricating oil, lubricating grease, mineral oil, petroleum,hydraulic oil, paraffin oil, spindle oil, light and heavy fuel oil,diesel oil, kerosene, gasoline, benzene, oil carried liquid organicpesticides, vegetable oils and fats, animal oils and fats, and emulsionsof the said products.

Another application of the dry product of the present invention isthrough dispersal onto the surface of oil floating on and contaminatingwater wherein the carrier containing the amorphous silica can float onthe oil/water interface, or the carrier can be dense enough to sink,depending on the contaminant recovery system one chooses prior toremediation/decontamination. In the case of a floating carrier, theamorphous silica, within seconds, absorbs the oil film onto both itselfand the carrier to create a bound, agglomerated matrix, easily becomingcollectable and ready for remediation. In the case of a dense, heavierthan water carrier, the oil is immediately absorbed by the amorphoussilica that has coated the carrier's surfaces and the agglomerate sinksto the bottom of water for recovery and disposal. Once absorption iscompleted, the residue is easily swept up, or in the case of oil onwater, the bound mass is easily collected by common means used tocollect oil spills such as skimmers. For oil spills on water, the EPAoutlines mechanical containment or recovery as the primary line ofdefense against oil spills in the U.S. The present invention candramatically aid timely and more efficient containment and recovery.

In order to further illustrate the present invention and its advantages,the following specific examples are given, it being understood that suchexamples are intended only as illustrative and not limitative.

Example 1

Dry products of the present invention containing untreated syntheticamorphous silica/carrier admix and controls were sprinkled (approx. ¼inch) onto uniform (approx. 5 inch diameter) spots of oil stain onconcrete pavers. The oil stains were caused by leaking motor oil from atruck engine. After several hours the residue was swept off the stainand collected. Observation documented the following results;

Product Result (a) 30 mesh sand no effect, stain remained (b) 2.2% CabotEH-5 silica admix in stain completely disappeared sand (c) BASF 30/60grade lightened stain, stain remained Attasorb ® RVM clay (d) 4% CabotM-5 silica admix in 30/60 stain completely disappeared Attasorb ® (e)Home depot sawdust no effect, stain remained (f) 8% Cabot EH-5 silicaadmix in stain completely disappeared sawdust

Example 2

The Example 1 tests were repeated on asphalt with products (a) and (b).The result was excellent stain removal performance of (b). The staindisappeared on this difficult surface vs. no effect of the control (a)where the stain remained.

Example 3

250 ml. of water was placed into a 400 ml. beaker. 10 gr. of Valvoline®SAE 30 motor oil was placed onto the water surface to represent an oilspill. Dry products of the present invention and controls were sprinkledonto the floating oil to determine the quantity of product necessary toabsorb the oil and the resultant nature of the absorbate for recoverypurposes.

Approximate amount by weight and percentage of product required Productto absorb all oil Result Attasorb ® 30/60 15 gr., 150% Absorbs oil,sinks, disperses, non-recoverable, leach able 4% Cabot EH-5 7 gr., 70%Absorbs oil, floats as a compact silica admix in matrix, morerecoverable 30/60 Attasorb ® Sawdust 5 gr., 50% Absorbs oil, floats,breaks up on surface (as reported by EPA) impeding recovery 8% CabotEH-5 3 gr., 30% Absorbs oil to a floating silica admix in recoverabletight matrix. sawdust

In the foregoing specifications, the invention has been described withreference to specific preferred embodiments and methods. It will,however, be evident to those skilled in the art that variousmodifications and changes may be made without departing from the broaderspirit and scope of the invention as set forth in the appended claims.

What is claimed is:
 1. A dry product consisting essentially of amorphoussilica combined with a dry, inert granular carrier.
 2. The dry productof claim 1 wherein said amorphous silica is between 0.2% and 35% byweight of said dry product.
 3. The dry product of claim 1 wherein saidcarrier is an inert inorganic carrier.
 4. The dry product of claim 3wherein said inorganic carrier is selected from the group consisting ofclays, including attapulgite clay, perlite, vermiculite, crushed glass,volcanic ash and sand.
 5. The dry product of claim 1 wherein saidcarrier is an inert organic carrier.
 6. A dry product consistingessentially of amorphous silica combined with a dry, inert carrierwherein said carrier is an inert organic carrier selected from the groupconsisting of peat moss, straw, hay, sawdust, ground corncobs, floursand coconut coir.
 7. The dry product of claim 1 wherein said carrier isan inert synthetic carrier.
 8. The dry product of claim 7 wherein saidcarrier is selected from the group consisting of polyurethane,polyethylene and polypropylene.